Proper watering of pot plants is a difficult problem. Too much water causes rotting of the plant roots. Too little water causes improper root development. It is recommended that the soil of pot plants be allowed to almost dry out before additional water is added, but this advise although good is not easy to follow because it is difficult to tell just how wet the soil is in the bottom of the pot. Many so-called self-watering pots have been made, but these are not entirely dependable and satisfactory since with many excessive amounts of water may be lost by evaporation resulting in underwatering of the plant, and with others excessive soil wetting may occur to cause rotting of the plant roots. There are some of the problems which the present invention seeks to solve.